Centrifuge tubes of various sizes are used in large quantities in chemical and microbiological laboratories. "Microfuge tubes" or "Eppendorf tubes" are predominantly manufactured in 0.5-ml and 1.5-ml sizes, and are usually equipped with polyethylene caps. Many of the manipulations that require the use of microfuge tubes are performed in water baths or on heating blocks. Often on boiling, the caps on the tubes pop open and the contents are forced out of the tubes, resulting in the loss of valuable samples. Various racks that hold centrifuge tubes, and particularly microfuge tubes, are commercially available, but most of the commercial products have no means for the prevention of the opening of polyethylene caps due to pressure caused by high heat. Moreover, there is no holder for microfuge tubes that could go directly from a heating block to a water bath and then to a bench. Due to these inconveniences and the usually high price of the commercial racks, scientists often make styrofoam "floatees" of their own. They usually punch holes the size of microfuge tubes, using a cork-borer, in a thin piece of styrofoam. The tubes, held firmly, float on top of the boiling water bath [Blumberg Methods in Enzymology 152 3 (1987)]. The homemade floatees are picked out of hot water baths with forceps and are transferred to heating blocks or to a bench. While these floatees are very inexpensive and convenient in that, since the whole rack floats, one does not need to adjust the level of water in the bath, valuable samples can be lost when the forceps used for manipulation slip, or when the microfuge tubes pop open due to high heat. The styrofoam floatees also tend to warp with exposure to high heat resulting in uneven heating/cooling of samples in different positions. There is a great need for centrifuge tube holders that are devoid of these disadvantages, can be directly transferred between heating blocks and water baths, have handles that facilitate manipulation, and have means for preventing the centrifuge tube caps from popping open.
U.S. Pat. No. 4,599,314 is directed to a specimen tray for holding a number of vessels which may be used in cell culture studies. Each vessel has an individual, removable cover. An overlying lid is adapted to cooperate with the specimen tray. The lid includes a plurality of openings that are co-incident with the openings on the tray. When the lid is in place, the top walls of the vessel covers project into the openings of the lid. A pressure sensitive tape can then be applied over the lid and the exposed surfaces of the covers, thereby releasably securing the covers to the lid. The tray has legs that are not pivotable, and has no handles. The pressure sensitive tapes employed for securing the vessel covers in place would not withstand low or elevated temperatures.
U.S. Pat. No. 1,653,244 relates to medicine trays used in hospitals. Pivotally connected to the tray interiorly of its ends are U-shaped handles which are movable from horizontal storage positions to upwardly extending carrying positions.
U.S. Pat. No. 4,609,237 discloses a food storage container having handles that are pivotable between horizontal and vertical positions. Detent means are provided for maintaining the handles in the desired position.
Floatable centrifuge tube holders that overcome the disadvantages of the foregoing are desired.